The “stand-alone” application, where the chatbot runs on a single computer, integrates mostly some sort of system interface, allowing your chatbot to control certain aspects and functions of your computer, such as playing media files, or retrieving documents. It usually also has a graphical component built in, as well, in the form of an avatar (often female) that enhances interaction, thus improving user’s experience.
The word robot is derived from the Czech noun robota meaning “labor”, and is an accomplishment of the cubist painter and writer Josef Capek, older brother of novelist and playwright Karel Capek. The word robot first appeared in 1920 in the Karel Capek’s play “RUR” (“Rossum’s Universal Robots”) and since then this play popularized the word invented by playwright’s brother.
The process of building, testing and deploying chatbots can be done on cloud-based chatbot development platforms offered by cloud Platform as a Service (PaaS) providers such as Oracle Cloud Platform  and IBM Watson. These cloud platforms provide Natural Language Processing, Artificial Intelligence and Mobile Backend as a Service for chatbot development.
Certainly for Facebook, this is much more about extracting marketing dollars than it is about breaking new ground in software development. Because by studying user’s interactions with these bots, Facebook will continue to build their understanding of how consumers are interacting with brands and gain additional insight into what products they like and content they consume. That can only mean more value to marketers and thus more dollars for Facebook.
Yes. Messenger bots are approved by Facebook before being made available inside the Messenger app so you can rest assured that they aren’t trying to steal your identity (or anything else). What’s more is a bot is tied to a Facebook page and a Facebook app making it all the more inconvenient to use for fraudulent activity. That said, don’t exchange private and/or personal information with a bot. Finally, because Messenger doesn’t support credit cards and purchasing just yet, anything you buy will likely be done via a browser with a bot aiding you so far as to place an order. If you want, you can always block a bot.